A keyboard is a peripheral device for inputting characters or commands into an information apparatus such as a desktop computer, a notebook computer, a mobile phone or a tablet computer. Generally, the keyboard has plural keys. When one of these keys is depressed by the user's finger, a corresponding signal is issued to the information apparatus, and thus the information apparatus executes a function (e.g. the function of inputting a character).
Generally, when the computer is no longer used by the user for a certain time period, a backlight module of the display screen of the computer may be turned off or the computer may enter a sleep mode or a hibernation mode. When the computer is used by the user again, it is necessary to press a key of the keyboard in order to turn on the backlight module of the display screen or wake up the computer from the sleep mode or the hibernation mode. As known, the way of operating the conventional keyboard is not user-friendly. Moreover, if the user erroneously judges that the computer is turned off, the user may restart the computer. Since the computer is not normally turned off, the starting process of the computer may shorten the use life of the computer or even lose important data of the computer.
Recently, a keyboard having an illuminating function has gradually become the mainstream in the market. Generally, the illuminating function of the conventional keyboard is enabled or disabled manually. The illuminating function of the keyboard is usually enabled by the user in the dim environment. However, after the keyboard is enabled, the user often forgets disabling the illuminating function of the keyboard. Consequently, even if the keyboard is used in a bright environment or the keyboard is not used by any user, the light-emitting element still emits the light beam. In other words, the use of the conventional keyboard has the problem of wasting electric power.
For solving the above drawbacks, a keyboard with a function of sensing whether an object enters a sensing range is disclosed. FIG. 1 is a schematic cross-sectional view illustrating a conventional keyboard with a function of sensing whether an object enters a sensing range. This keyboard 1 is disclosed in Chinese utility model patent Nos. CN201440241. As shown in FIG. 1, the keyboard 1 comprises a keycap layer 11, a light guide plate 12, a metal resilience layer 13, a membrane circuit board 14, at least one light emitting diode 15, an induction processing device 16, an induction antenna 17, and a keyboard housing 18. The induction processing device 16 is located at a side of an inner portion of the keyboard housing 18. The induction antenna 17 is electrically connected with the induction processing device 16. When a user is located near or far from the keyboard 1, the induction processing device 16 senses whether the user enters the sensing range according to the detecting result of the induction antenna 17. Consequently, the light emitting diode 15 is automatically turned on or turned off.
In Chinese utility model patent Nos. CN201440241, the induction antenna 17 is directly printed on the membrane circuit board 14 or circularly disposed within the keyboard housing 18. In case that the induction antenna 17 is printed on the membrane circuit board 14, the induction antenna 17 should be separated from the traces of the membrane circuit board 14. Under this circumstance, the position of installing the induction antenna 17 is restricted, and the fabricating process is complicated. Whereas, in case that the induction antenna 17 is circularly disposed within the keyboard housing 18, the size of the keyboard housing 18 should be large enough to accommodate the induction antenna 17. Under this circumstance, the keyboard fails to meet the requirements of light weightiness, slimness and miniaturization. In the above two situations, since the induction antenna 17 is very close to the metal resilience layer 13, a signal interference problem occurs.
Therefore, there is a need of providing an improved keyboard with a function of sensing whether an object enters a sensing range in order to eliminate the above drawbacks.